Air motor valve

ABSTRACT

An air motor including an outer casing having a three-lobed chamber defined in one end thereof which rotatably receives a cylindrical rotor. Air under pressure is fed through a suitable inlet into one end of the chamber. Two pairs of perpendicularly disposed vanes are slidably disposed in slots in the rotor and radially extend from the rotor into unoccupied outer portions of the three-lobed chamber. The vanes have relieved portions along the sides thereof to provide, along with the slots in the rotor, communication between the air inlet and the outer portions of the three-lobed chamber. Passage of air under pressure through the air inlet into the outer portions of the chamber acts upon the vanes to cause rotation of the rotor. The valve of the invention is included in the outer casing to vary the passage of air in order to control the rotation speed of the rotor.

United States Patent [72] Inventor Oren V. Northcutt Box 176, Point,Tex. 74572 [21] Appl. No 882,903 [22] Filed Dec. 8, 1969 Division 01Ser. .\'o.639.767,!\1ay 19. 1967. Pat. No. 3.498.186 [45] Patented July6, 1971 [54] AIR MOTOR VALVE [56] References Cited UNITED STATES PATENTS1/1928 Jones Primary ExaminerClarence R. Gordon Attorney-Richards,Harris & Hubbard ABSTRACT: An air motor including an outer casing havinga three-lobed chamber defined in one end thereof which rotatablyreceives a cylindrical rotor. Air under pressure is fed through asuitable inlet into one end of the chamber. Two pairs of perpendicularlydisposed vanes are slidably disposed in slots in the rotor and radiallyextend from the rotor into unoccupied outer portions of the three-lobedchamber. The vanes have relieved portions along the sides thereof toprovide, along with the slots in the rotor, communication between theair inlet and the outer portions of the three-lobed chamber. Passage ofair under pressure through the air inlet into the outer portions of thechamber acts upon the vanes to cause rotation of the rotor. The valve ofthe invention is included in the outer casing to vary the passage of airin order to control the rotation speed of the rotor.

PATENTED JUL BIS?! 3,590,875

FIG. 4

INVENTOR OREN NORTHCUTT ATTCRNEY BACKGROUND OF THE INVENTION 1. Field ofthe Invention This invention relates to rotary air motors, and moreparticularly to rotary air motors in which radial vanes slidablydisposed in a rotor are acted upon by air under pressure to causerotation of the rotor.

2. Description of the Prior Art Air motors have heretofore beendeveloped in which a source of pressurized air is connected through acasing inlet to a casing chamber containing a rotor. Radially extendingvanes are slidably disposed in the rotor so that the vanes extendingfrom one side of the rotor are acted upon by the incoming pressurizedair to cause rotation of the rotor. The air then passes through anoutlet formed in the wall of the chamber. As the rotor turns, the vanesare forced radially inwardly by the sidewalls of the chamber until thevanes are again rotated to a position where the vanes are again extendedto be acted upon by the incoming pressurized air.

Such rotary air motors have been found to be generally useful forpowering hand tools and the like, but have often not been completelysatisfactory with respect to starting torque and available output power.As a result, it has often been necessary to construct such previouslydeveloped air motors with relatively large dimensions to providesufficient output power, thereby rendering the motors generally uselessfor many applications involving small working spaces or delicate work,due to the resulting bulky size and undue weight of the motors.

Further, previously developed rotary air motors which provide drivingforces only to vanes on one side of a rotor have been found to stall insome instances, as for instance when the rotor becomes loaded at theinstant a vane is disposed over the air outlet. Similarity suchpreviously developed motors have often been difficult to start when avane is adjacently disposed over the air outlet. Air motors usingpressurized air to drive only vanes on one side of the rotor have alsobeen subject to undesirable vibrations due to the unbalanced nature ofsuch motors.

SUMMARY OF THE INVENTION In accordance with the present invention, arotary air motor is provided wherein pressurized air drives a rotor onthree sides thereof, thus providing improved rotor balance and efficientdriving force, in addition to reducing stalling of the motor. The motorcomprises a casing having a three-lobed chamber formed therein andincluding an air inlet into the chamber. A rotor is disposed in thecenter portion of the chamber and two pairs of perpendicularly disposedvanes are slidably disposed in the rotor, each of the vanes adapted toradially extend from the rotor into unoccupied portions of the threelobes. Each of the vanes also includes relieved portions to providecommunication between the air inlet and the outer portions of the threelobes. Passage of air under pressure through the air inlet into theouter portions of the lobes acts upon the radially extending portions ofthe vanes to provide rotation to the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding ofthe present invention and for further objects and advantages thereof,reference may FIG. 3 is an exploded view of the rotor and associatedvane members of the motor shown in FIG. 1;

FIG. 4 is a fragmentary section of a portion of the casing shown inFIGS. 1 and 2;

FIG. 5 is a view of an alternative configuration of a vane member foruse with the present invention; and

FIG. 6 is an enlarged view of a portion of the air control valve shownin FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the presentair motor is designated generally by the numeral 10 and includes ahollow casing 12 which has an air hose connection member 14 pivotallyfastened in one end thereof. The casing I2 rotatably receives in anotherend a rotor 16 which is integrally connected to an output shaft 18. Aswill now be described in detail, the passage of air under pressurethrough the member 14 and the casing 12 causes rotation of the rotor 16and the output shaft 18.

Casing 12 includes a central bore 20 which extends along thelongitudinal axis of the casing and communicates at one end with athree-lobed chamber 22 defined in an enlarged diameter casing endportion 24. As best shown in FIG. 2, the three-lobed chamber 22 isdefined by three symmetrically spaced counterbores designated generallyas 26, 28 and 30. A central counterbore 32 (FIG. 1) has a greater depththan the counterbores 26, 28 and 30. Counterbore 32 defines threesidewall portions 34, 36 and 38, which are disposed about the outerperiphery of rotor 16.

Rotor 16 comprises a cylindrical body having a slightly smaller diameterthan the counterbore 32 so that the rotor may be easily rotated withinthe chamber 22. An O-ring seal 40 fits between the bottom end of thecounterbore 32 and an end portion 42 of the rotor 16. A thrust bearing44 and a thrust race 46 are disposed between the upper portion of therotor 16 and a housing 48 in which the output shaft 18 is rotatablyjournaled. Housing 48 is connected to the enlarged diameter casing endportion '24 by suitable bolts 50 which are threadedly received bysuitable holes 52 in casing end portion 24.

As shown in FIGS. 2 and 3, rotor 16 includes perpendicularly disposedslotted portions 54 and 56 which extend along longitudinal portions ofthe rotor and which intersect along the axis of rotation of the rotor toform an X-shaped passageway 57 through the center of the rotor. Endportion 42 is connected to the rotor 16 by suitable screws 58 andincludes a central opening 60 which communicates with the passageway 57and the central bore 20 of casing 12.

The rotor 16 slidably receives in slots 54 and 56 two pairs of matchingvane members 62, 64, 66 and 68. Vane members 62 and 66 are identical'inconstruction and both include a base portion 70 and an integralextension 72 of reduced width. A relieved portion 74 is formed along oneside of each of the vane members 62 and 66. Similarly, vane members 64and 68 are constructed in a like manner and both include a base portion76, an extension 78 of reduced width and a relieved portion 80 along oneside thereof. The surfaces of each of the vane members are smooth inorder to easily slide within slots 54 and 56.

As most clearly shown in FIG. 3, the matching pair of vane members 62and 66 are slidably disposed in slot 54 with the base portions 70disposed adjacent the end portion 42. The matching pair of vane members64 and 68 are slidably disposed in slot 56 with the base portion 76disposed adjacent the end of rotor 16 which is connected to the outputshaft 18. When the motor is assembled, portions of the vane membersextend radially outwardly from rotor 16 (FIG. 2) into the unoccupiedlobed portions 26, 28 and 30 of chamber 22. A

small amount of clearance is provided between the dimensions of chamber22 and the combined widths of each pair of vane members.

As shown in FIGS. 2 and 4, the lobed portions of the chamber 22 includeoutlet slots 82, 84 and 86 which provide direct communication betweenthe lobed portions and the outside atmosphere. The outlet slots aredisposed on one side of the lobed portions so that the relieved portions74 and 80 of the vane members face away from the slots during themajority of rotation in the lobed portions. FIG. 4 shows that the outletslots may be formed in the sides of casing 12 with a circular cuttingmember so that the area of the outlet slots increases from a relativelysmall slotted portion opening into the lobed portions to a relativelylarge slotted portion at the outside surface of the casing 12. A mufflermember 88 includes chamfered portions 90 and 92 which allows the member88 to be fixedly connected between the casing end portions 24 and thehousing 48. Muffler 88 includes three spaced holes 94, 96 and 98 forexhausting air from the outlet slots in the motor to the atmosphere.

In operation, air under high pressure, generally between lOO to 200pounds per square inch, is supplied from a suitable source through thecasing central bore 20 and through the opening 60 in the rotor 16. TheO-ring 40 prevents air from leaking around the outside surface of rotor16, and thus the air is forced through the passageway 57 in rotor 16which is formed by the intersection of the slots 54 and 56. In theposition of the rotor 16 shown in FIG. 2, air under pressure would thusbe forced through the slot 54 and the relieved portion 80 of vane member68 into the unoccupied lobed portion 30 of the chamber 22. The vanemember 68 will prevent the air from exhausting through slot 84, and theresulting force provided by the pressurized air will act upon vane 68 tocause rotation of the rotor 16 in a clockwise direction illustrated bythe arrows 99. After the vane member 68 rotates past outlet slot 84, theair under pressure will exhaust through the outlet slot 84 and theopening 94 in the muffler 88. A small clearance will exist between vanemembers 68 and 64, as the force of the air through relieved portions 80will tend to force the vane members radially outwardly until the vanemembers abut the surface of chamber 22.

Simultaneously, air under pressure will be admitted through slot 56 andthe relieved portion 74 of the vane 62 into the lobed portion 28. Theforce provided by the air under pressure will act upon vane member 62 toprovide an additive force of rotation in a clockwise direction. Afterthe vane member 62 rotates past the outlet slot 86, the air will beexhausted through outlet slot 86 and opening 96. Also, simultaneously,air under pressure will be forced through the rotor slot 54 and therelieved portion 80 of the vane member 64 into the lobed portion 26,thereby acting upon the vane member 64 to provide a third additive forceof rotation in a clockwise direction. Only when the vane member 64rotates past outlet slot 82 will the air in lobed portion 26 beexhausted through slot 82 and muffler opening 98. The vane members thusact as valves to control the passage of air in the three-lobed chambers.It will be understood that at all times the pressurized air is actingupon three vane members to provide a generally balanced and efficientforce to the rotor 16.

In the position of the rotor 16 illustrated in FIG. 2, the outer edge ofvane member 66 abuts the wall portion 38 and air under pressure will beblocked from passing through the relieved portion 74 of vane member 66.However, after a relatively small arc of clockwise rotation by rotor 16,vane member 62 will be cammed radially inwardly by the walls of thelobed portion 28, thereby forcing the vane member 66 radially outwardly.The force of air passing through the relived portion 74 will then forcevane member 66 against the walls of the lobed portion 30, leaving asmall clearance between the edges of vane members 62 and 66.

Similarly, upon clockwise rotation of the rotor 16 from the positionillustrated in FIG. 2, the vane member 68 will be cammed radiallyinwardly by the walls of the lobed portion 30, thereby forcing the vanemember 64 further radially outwardly. Such action will continue untilthe vane member 68 is in substantial engagement with the wall portion36, thereby blocking the passage of pressurized air through the relivedportion 80 thereof. It will thus be understood that similar slidingmovements of the vane members will occur during each revolution of therotor 16, with air under pressure acting upon three vane members duringthe majority of each revolution. Such consistent driving action againstthree vanes causes very efficient and powerful rotative forces to beimposed upon the rotor 16 and the output shaft 18.

FIG. 5 shows an alternative construction of a vane member for use in thepresent motor, wherein two relieved portions 102 and 104 are defined inone side thereof instead of the singular relieved portion previouslydescribed. The provision of the two relieved portions has been found tobe advantageous in providing uniform distribution of pressurized airinto the three-lobed portions of the chamber 22.

The casing 12 is preferably made from aluminum and provided with a hardanodized finish. The rotor 16 is preferably constructed from stainlesssteel and heat treated. The vane members utilized in the presentinvention are preferably made from a suitable plastic material, such asacetal resin of composition (-OCI-l derived from polymerization offormaldehyde and sold under the trademark "Delrin".

In order to control the flow of air to the present motor, a valvecomprising a plunger 106 and a suitable O-ring seal 107 is slidablydisposed in a bore 108 which extends radially through the casing 12.Bore 108 intersects with a reduced diameter end portion 109 of thecentral bore 20 at a chamber 110. A bore 112 also extends through casing12 to open into the other end of the chamber and to form an annularvalve seating shoulder 113. A plug 114 is threadedly received in bore112 to prevent the escape of air therethrough. As shown in FIGS. 1 and6, a resilient valve washer 116 is loosely connected by a suitable screw118 to an end of plunger 106. Screw 118 extends outwardly from the endof plunger 106 for a distance so that valve washer 116 may move into orout of contact with the end portion of plunger 106. Plunger 106 alsoincludes a reduced diameter portion 120 which is disposed generally inthe region of chamber 110. A venting channel 121 is formed across theend of plunger 106. A counterbore 122 is defined in the rearmost end ofthe casing 12 and opens through a port 123 into chamber 110. A largerdiameter counterbore 124 opens from counterbore 122.

A circular surface 125 is formed between the counterbores 122 and 124 toreceive a portion of a ball-like rear element 126 of the air hoseconnector member 14. Element 126 is held in place inside counterbore 124by a suitable washer 128 and retainer snap ring 130. An O-ring 132 isdisposed about the ball-like portion 126 in order to prevent leakage ofair. An opening 133 is defined through member 14 and the end of member14 is provided with ridged portions 134 to allow attachment thereto of asuitable air hose. Member 14 may thus be pivoted with respect to thecasing 12 to allow free usage of the present motor 10 in inconvenientworking locations. A wire strainer 136 may be disposed in counterbore122 to strain out impurities in the pressurized air.

To operate air motor 10, a suitablesupply of pressurized air isconnected to member 14 and plunger 106 is manually depressed to theposition illustrated in FIG. 1. Air under pressure is provided throughthe opening 133 in member 14 to the counterbore 122. The air will thenpass through the port 123 into chamber 110, and from thence into thecentral bore 20 to drive rotor 16 in the manner previously described.The pressurized air passes behind valve washer 116 and provides a forcetending to move the plunger 106 radially outwardly. Consequently, manualdepression of the plunger 106 is required throughout operation of thedevice.

Whenever it is desired to stop the operation of the rotor 16, the manualforce on plunger 106 is reduced and the plunger 106 is allowed to travelradially outwardly due to the force of air behind valve washer 116.Valve washer 116 is then moved along with the head of screw 110 tofirmly abut shoulder 113 and to obstruct port 123. The flow of airthrough the central bore 20 is thus completely stopped and the rotationof rotor 16 is interrupted.

The loose attachment of valve washer 116 to screw 118, best shown inFIG. 6, allows an intermediate speed or operation of the present airmotor, in addition to reducing the amount of manual force necessary todepress plunger 106. When the flow of air is completely stopped andvalve washer 116 is firmly abutted against shoulder 113, initialdepression of plunger 106 only moves the screw 118 radially inwardly.The relatively small area of the head of screw 118 will allow ease ofdepression although substantial air pressure exists against the valewasher 1 16 in the bore 1 12.

Air under pressure will then pass through the small annular openingbetween screw 118 and valve washer 116 to operate the air motor at anintermediate speed. Air will continue to pass between the annularopening between the screw 118 and valve washer 116, and through ventingchannel 121, even when the end of plunger 106 abuts valve washer 1 16 asshown in FIG. 6. Upon further manual depression of plunger 106, valvewasher 116 will be unseated from shoulder 113, as shown in FIG. 1, toallow a greater amount of air under pressure to flow to the air motor.The present valve construction thus enables a dual speed operation ofthe air motor, in addition to a deenergized condition.

The present device thus provides a very lightweight, yet efficient andpowerful rotary air motor which is convenient for use with such tools aspower wrenches and the like. The positive drive provided simultaneouslyon three rotor vanes according to the present invention reduces stallingof the air motor and increases the rotative power without increasing theweight thereof. The present motor is constructed from a minimum of partsand has been found to be durable over an extended period of use under avariety of difierent conditions.

Whereas the present specification has been described in considerabledetail with respect to a preferred embodiment, it is to be understoodthat this description is merely for purposes of illustration and thatchanges or variations in the described embodiment may be made by personsskilled in the art without departing from the true scope and spirit ofthis invention as is solely defined in the appended claims.

What 1 claim is:

1. An air motor valve for regulating the passage of compressed airthrough an elongated passageway extending through an air motor housingcomprising:

a fluid inlet counterbore in one end of said housing and hav' ing a portlaterally offset from the axis of said passageway,

a circular chamber extending through a side of said housing andproviding communication between said port and said passageway,

a manually slidable plunger having an end portion disposed in saidchamber and having a portion of reduced diameter adapted to be movedadjacent the end of said passageway,

a venting channel defined across the face of said end portion,

a screw member having a head at the end thereof rigidly connected to andextending from said plunger end portion, and

a resilient valve washer disc having an aperture in the center thereofof a diameter less than the diameter of said screw member head, saidwasher disc loosely encircling said screw member and movable along thelength thereof between the end of said plunger and said head, wherebytwo difi'erent amounts of air may be selectively allowed to pass throughsaid passageway in order to operate said air motor at two differentspeeds or wherein the passage of air may be completely blocked independency on the relative position of said plunger and said valvewasher disc.

1. An air motor valve for regulating the passage of compressed airthrough an elongated passageway extending through an air motor Housingcomprising: a fluid inlet counterbore in one end of said housing andhaving a port laterally offset from the axis of said passageway, acircular chamber extending through a side of said housing and providingcommunication between said port and said passageway, a manually slidableplunger having an end portion disposed in said chamber and having aportion of reduced diameter adapted to be moved adjacent the end of saidpassageway, a venting channel defined across the face of said endportion, a screw member having a head at the end thereof rigidlyconnected to and extending from said plunger end portion, and aresilient valve washer disc having an aperture in the center thereof ofa diameter less than the diameter of said screw member head, said washerdisc loosely encircling said screw member and movable along the lengththereof between the end of said plunger and said head, whereby twodifferent amounts of air may be selectively allowed to pass through saidpassageway in order to operate said air motor at two different speeds orwherein the passage of air may be completely blocked in dependency onthe relative position of said plunger and said valve washer disc.